Abstract: A specific antibody against prostaglandin F_2α (PGF_2α) was obtained from rabbits immunized with PGF_2α conjugated to bovine thyroglobulin (BTG) by N, N-Carbonyl-diimidazole (CDI). A sensitive, accurate, precise and convenient radioimmunoassay for PGF_2α has been established in our laboratory by use of this antibody, and the normal levels of PGF_2αin plasma and tissues of human and animals were measured.